Just when you thought it was safe to go back in the water… Subprime lending has come roaring back.

But this time, reckless financial innovation isn’t being hatched on Wall Street. Instead, state governments are angling to “monetize” first-time homebuyer tax credits so borrowers can purchase homes with little or no money down.

If this sounds eerily similar to the type of lending practices that got us into this mess, well, it should.

The federal government, as part of the recently passed economic stimulus package, will refund first-time homebuyers up to $8,000 if they meet certain eligibility requirements. The program is frequently cited as one of the myriad reasons a bottom in the housing market is imminent.

Critics, however, argue that rebates don’t end up in a buyer’s pockets until his or her 2009 tax returns are filed – even though rebates are credits, not just deductions.

Homebuilders like Pulte Home (PHM), Lennar (LEN) and KB Home (KBH), along with their lobbying arm, the National Association of Homebuilders, have thrown their full weight behind the rebate program, but say it still doesn’t go far enough.

In an effort to boost home buying — even for marginally qualified borrowers — a number of states are finding creative ways to advance the tax credit to buyers on the day they get their new keys, rather than having to wait for next year’s refund check. This allows buyers to pay for things like closing costs, mortgage points – or even the down payment.

States are employing schemes whereby they offer prospective buyers low or no-interest loans for the amount of the tax credit, due upon of receipt of their money from Uncle Sam. If the borrower doesn’t make good, the loan becomes a junior lien on the property, with an interest rate that is far from usurious – usually just a bit over the prime lending rate. Missouri was the first state to launch such a program, and has since been joined by Delaware, New Mexico, Pennsylvania, Tennessee and others. States are even lobbying the IRS to deposit the refunds directly to the states, rather than to the home buyers, in order to circumvent non-payment. The IRS, for its part, “is reviewing” this idea.

In Washington, the state Housing Finance Commission runs a tax credit bridge-loan program, which it hopes will grow in the coming months. Not surprisingly, local real-estate professionals are behind the initiative. Washington Association of Realtors president Bill Riley told the San Francisco Chronicle he believes around half of would-be first-time buyers in his state “cannot save enough money for the down payment and closing costs.”

Exactly. That’s the point. This is precisely what differentiates a “would-be” home buyer and a home buyer. And that’s the way it should be.

If the federal government wants to subsidize home ownership, fine. It’s already proven unwilling to learn the lessons of Fannie Mae (FNM) andFreddie Mac (FRE) about the costs of jamming borrowers into homes they can’t afford. But these rebates should at least be limited to borrowers that meet even the most modest requirements to buy a home in a responsible manner.

The Federal Housing Administration — another vehicle for government-backed mortgages where taxpayers bear all the risk — gives out loans that require borrowers to post a meager 3% down payment. If a “would-be” homeowner cannot scrape together this amount of cash, that person should rent and save their pennies. They should not receive a no-interest loan from the state government. This is not discrimination, this is not redlining, its common sense.

In a rush to prop up home prices and delay the ultimate day of reckoning for the vast majority of US real-estate markets, the federal government — and now state governments as well — insist on coercing taxpayers to over-leverage themselves and take on a debt burden they cannot truly afford.

From the looks of it, Washington is leading by example.

Top Stocks blogging partner Todd Harrison is founder & CEO of Minyanville.com. This post was written by Minyanville Contributor Scott Andrew Jeffery.